Brain and decision making: a multidisciplinary approach for studying social behavior – SocialBrain

1. Scientific background and objectives Neuroscientists, psychologists and economists have recently begun to jointly study how strategic thinking and emotions related to reward, self-interest, or fairness regulate human individual and social behaviour. Our research program intends to combine efforts across these disciplines in order to study the neural bases of human decision making in social contexts. Experimental economists and psychologists have highlighted the limits of rational theory for explaining and predicting how people act in social contexts. Alternative models based on social preferences, that integrate the role of emotions such as shame and guilt, attempt to explain the substantial evidence for reciprocity and trust in social interactions, which argues against any rational self interest model. The neural and biological bases of these behaviours are still not completely understood. Studying cooperation and reciprocity is to a large extent studying the mechanism for enforcing or reinforcing pro-social behaviour, which includes both positive (reward of pro-social behavior) and negative (punishment of social norm violations) drives. In social settings, violating the norm affects members of a group in terms of status, reputation and exclusion. Punishment of 'free-riders' in a society where cooperative behaviour is expected is believed to be the main way in which norms are maintained, since the fear of punishment can deter selfish behaviour. Punishment is costly, and is inherently linked to the degree to which norms are internalized. We will explore these mechanisms from economical, psychological and neuroscientific perspectives. 2. Description of project, methodology We propose to study the mechanisms of choice strategies from a game theory perspective using functional neuroimaging methodologies. We shall focus on the way strategic thinking and emotions drive cognitive strategies employed in human cooperation and social interactions depending upon social context (punishment versus social exclusion). The findings will be used for developing new theories that address the evolution and neural underpinnings of the human social brain. We will conduct a set of three fMRI studies on punishment of violation of social norms and social exclusion. 3. Expected results We expect our fMRI results to show that: (1) Punishment and rewarding behaviours depend upon context (fMRI study 1 and 2): thus subjects in our games will punish more when only a punishment option is available and will reward more when only the reward option is available. We expect to observe enhanced OFC activity when the subjects receive unfair offers, thus responding to violation of social norms, and when the subjects choose actions according to social norms, e.g making fair offers. Moreover, this activity should vary according to the context, thus complementing our expected results in patients with OFC lesions. (2) Finally, in a last fMRI experiment, we shall investigate whether the experience of punishment involves common and/or distinct neural substrates for reception or administration of monetary punishment (loss of money) as compared to social punishment (social exclusion) in a new experimental setting involving a group of players. We can predict brain activities that mediate incentive and reward-related behaviours, specifically nucleus accumbens, ventral and dorsal striatum, and systems that mediate responses to violation of social norms, such as the orbitofrontal cortex, anterior cingulate (conflict between others' behavior and norms), with enhanced responses for social exclusion. Taken together, the present project has a multidisciplinary approach and will combine the expertise of two young researchers to investigate the neural mechanisms of human decision making in social contexts, helping to understand the neural substrates underpinning motivationally significant information related to reward and punishment of different nature (social exclusion as opposed to financial outcome), reception versus administration of punishment. Our research program will also clarify what makes individuals opt for collaboration and competition when they have the choice between these two options and what are the neural correlates of the emotions accompanying such strategic choices. The major novelty of this proposal is to address such questions at multiple levels (neuropsychology, brain imaging, modelling) and from multiple perspectives, adopting as unifying principle the conceptual framework of game theory.